We experimentally demonstrate the possibility of quasi-adiabatic conversion of ${{\rm LP}_{11}}$ modes to vortex modes in a twisted highly birefringent fiber with a gradually increasing twist rate. Based on the value of the effective indices, the ${{\rm LP}_{11}}$ modes are selectively converted to right- and left-handed circularly polarized vortex modes ${{\rm HE}_{21}}$ with a total angular momentum of $\pm {2}$ and to quasi-${{\rm TE}_{01}}/{{\rm TM}_{01}}$ modes with a total angular momentum of 0. Since the proposed conversion method has a purely topological origin, it is broadband in nature, in contrast to the methods based on resonant effects.

中文翻译：

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在逐渐扭曲的高双折射光纤中将 LP11 模式转换为涡流模式

我们通过实验证明了在扭曲率逐渐增加的扭曲的高双折射光纤中，${{\rm LP}_{11}}$模式准绝热转换为涡流模式的可能性。根据有效指数的值，${{\rm LP}_{11}}$模式被选择性地转换为右旋和左旋圆极化涡旋模式${{\rm HE}_{21}} $的总角动量为$\pm {2}$和准${{\rm TE}_{01}}/{{\rm TM}_{01}}$模式，总角动量为0. 由于所提出的转换方法具有纯粹的拓扑起源，因此与基于共振效应的方法相比，它本质上是宽带的。